The researchers that developed this task decribe it in DeVito et al. (2009) as follows:
Information Sampling Task
The IST (Clark et al. 2006) is a measure of ‘reflection–
impulsivity’. Subjects were told they would be presented
with ten trials in each of two conditions [fixed win (FW),
decreasing win (DW)] and that the task would last for
10 min. On each trial, a 5×5 matrix of grey boxes with two
larger coloured panels below it was presented. Subjects
were told to press on a box to reveal its colour and to open
as many boxes as they chose prior to deciding which of the
two colours they thought was in the majority amongst the
25 boxes. Boxes remain open for the duration of the trial to
minimise working memory load. To register their decision,
they pressed on one of the two coloured panels displayed.
In the FW condition, if the subject chose correctly, they
earned 100 points, but lost 100 points if they chose
incorrectly. In the DW condition, subjects begin with the
ability to win 250 points, but with every box they opened
the amount they could win decreased by 10 points. An
incorrect choice was still penalised with a loss of 100 points
regardless of the amount of boxes opened. Therefore, in the
FW condition, extensive information sampling prior to
decision was optimal, whilst in order to gain points in the
DW condition the subject must adjust to sample less
information. A variable inter-trial interval was used such
that the minimum trial duration was 30 s (e.g. if the subject
responded after 10 s, the inter-trial interval would be 20 s).
This feature was included to prevent unduly rapid responses
leading to shorter task duration and thus an earlier escape of
the experimental setting. This task is described in more
detail by Clark et al. (2006).
In Clark et al. (2006), they write:
In the present study, we used a novel Information Sampling Task (IST) to assess reflection impulsivity in chronic substance users. The objectives of the IST design were to derive a primary index of information sampling (rather than a speed–accuracy composite) in a task that placed negligible demands on visual processing and working memory. The IST presents a series of trials with an array of 25 grey boxes arranged in a 5 × 5 matrix. The grey boxes conceal an underlying assortment of squares (e.g., yellow and blue; Figure 1) on each trial. The subject was asked to decide which of the two underlying colors (yellow or blue) lay in the majority. The subject was able to open as many boxes as they wished to make that decision. Once opened, boxes remained visible for the duration of the trial to obviate working memory demands. Correct decisions were awarded a number of points, with trials blocked into two conditions. In the Fixed Win (FW) condition, a correct decision yielded 100 points, irrespective of the number of boxes opened. In the Decreasing Win (DW) condition, the number of available points decreased with every box opened. Consequently, the DW condition introduced a conflict between reinforcement and certainty: to maximize reinforcement the subject must tolerate high uncertainty, whereas sampling information until a point of high certainty would win very few points. Given preliminary evidence that drug users might be hypersensitive to reward (Bechara et al 2002 and Garavan and Stout 2005), we predicted that the DW condition would encourage impulsive responding and exaggerate individual differences.
Figure 1. Screen display for the Information Sampling Task. Each trial commences (left) with the presentation of 25 grey boxes arranged in a 5 × 5 matrix, covering a random assortment of two colors of squares; these two colors are displayed on panels at the foot of the screen. When the subject touches a box (middle), it opens to reveal its color. The subject must decide which of the two colors lies in the majority on the board. They are told they can open as many boxes as they wish to make this decision. They are told to touch the corresponding panel at the foot of the screen (bottom right) once they have decided which color is in the majority.
In addition, there is a description of the Information Sampling Task in the Cognitive Atlas.
DeVito, E. E., Blackwell, A. D., Clark, L., Kent, L., Dezsery, A. M., Turner, D. C., ... & Sahakian, B. J. (2009). Methylphenidate improves response inhibition but not reflection–impulsivity in children with attention deficit hyperactivity disorder (ADHD). Psychopharmacology, 202(1-3), 531-539.
Clark, L., Robbins, T. W., Ersche, K. D., & Sahakian, B. J. (2006). Reflection impulsivity in current and former substance users. Biological psychiatry, 60(5), 515-522.